Process for preparing oil-soluble sulfonic acids



United States Patent PROCESS FOR PREPARING OIL-SOLUBLE SULFONIC ACIDSEverett E. Gilbert, Flushing, and Benjamin Veldhuis, Al-

bertson, N. Y., assignors to Allied Chemical & Dye Corpioration, NewYork, N. Y., a corporation of New Yor No Drawing. Application March 18,1953, Serial No. 343,228

9 Claims. (Cl. 260504) This invention relates to a process for preparingoilsoluble sulfonic acids and more particularly to a process forpreparing such acids from hitherto substantially valueless wastematerials.

Oil-soluble sulfonic acids are useful in the preparation ofrust-proofing formulations, as emulsifiers, as diesel engine lubricantadditives and the like, and the demand for such oil-soluble sulfonicacids and sulfonates has increased steadily in recent years.

Oil-soluble sulfonic acids have been prepared in the past as byproductsin processes for the production of mineral white oils. In certain ofthese processes, an appropriate distillate or residual fraction of anaromaticcontaining petroleum oil is first purified by a light sulfuricacid treatment or by solvent extraction by conventional methods usingsuch solvents as nitrobenzene, liquid sulfur dioxide, furfural,dichlorodiethylether, phenol, etc. The purified fraction so obtained isthen sulfonated in one or more steps or dumps using 20% oleum, sulfurtrioxide or other appropriate sulfonating agent. This process sulfonatesthe aromatic and unsaturated constituents of the oil fraction. Uponsettling, the acid-oil mixture stratifies into two layers, onecontaining residual sulfuric acid together with sludge and green acids,i. e., Water-soluble hydrocarbon sulfonic acids, the other layercomprising oil containing dissolved oil-soluble sulfonic acids. Theoilsoluble sulfonic acids are usually extracted from the oil layer withsolvents such as alcohols. The yield of oil soluble sulfonic acidsobtained by this process is extremely low, usually from about to about10% based on the weight of the raifinate sulfonated.

As the demand for the oil-soluble sulfonic acids increased beyond thesmall quantity available as a by-prodnot in the production of mineralwhite oils as described above, additional quantities of sulfonates wereproduced as primary products of these petroleum oils without theconcomitant formation of white oil.

It has long been recognized that the solvent extracts obtained inrefining various petroleum fractions using nitrobenzene, liquid sulfurdioxide, furfural, dichlorodiethylether, etc., might be source materialsfor sulfonic acids, since they were known to contain high percentages ofaromatic hydrocarbons. Various types of extracts have been availablevarying in characteristics with the character of the oil purified. Theseincluded extracts from the manufacture of kerosene, light lubricatingoils, heavy lubricating oils, residual lubricants (bright stocks) etc.The extracts obtained in the above operations differ widely inviscosity, molecular weight, boiling range, and other physicalproperties.

Extracts obtained by solvent extraction from light distillates and lowviscosity lubricating oil stocks have found use in the preparation ofhydrocarbon sulfonic acids and sulfonates which are water-soluble andwhich possess surface-active properties which render them useful asdetergents.

Processes for utilizing extracts from solvent refining of intermediateviscosity lubricating oil stocks, for example, stocks having viscositiesup to about seconds Saybolt Universal viscosity (SUS), at 210 F. havebeen proposed for the preparation of oil-soluble sulfonic acids. Suchprocedures involve step-wise sulfonation of such intermediate viscosityextracts, with removal of sludge between steps, or the preparation ofdistillates or extracts of such extracts and sulfcnation of theraflinates from these operations to produce oil-soluble sulfonic acidsor mixtures of oil and water-soluble sulfonic acids. These processeshave not proven practical due to excessive sludge formation, poo-ryields of desired oil-soluble product, high labor costs due to theplurality of steps involved and the extra costs involved in refining theextract before sulfonation.

Attempts to utilize the extremely high viscosity extracts, i. e., thosehaving viscosities as high as about SUS at 210 F., have taken adirection similar to that utilized in treating the medium viscosityextracts, but without even the partial success achieved with the mediumviscosity extracts, since such operations fail to reduce sludgeformation on sulfonation sufliciently to make such sulfonationscommercially practicable.

We have now found that oil-soluble sulfonic acids suitable for use inthe preparation of lubricant additives, rustproofing compositions,emulsifiers for agricultural sprays, ingredients of cutting oils, asfat-splitting agents and the like, may be prepared with minimal sludgeformation by direct, single-step sulfonation with sulfur trioxide gas,in the presence of an inert liquid chlorinated hydrocarbon or nitratedaromatic hydrocarbon, of crude high viscosity aromatic-containingpetroleum extracts having Saybolt Universal viscosities (SUS) at 210 F.of at least about 100 seconds.

Thus, in accordance with our process, crude extracts of the characterdescribed may readily be sulfonated with formation of minimal quantitiesof sludge varying from virtually none to minor amounts which in no Wayinterfere mechanically with the operation of the process in suchrespects as agitation, pumping, etc. The absence of sludge formation insulfonations with sulfur trioxide of extracts of this character is quiteunexpected, as sulfonation of even much lower viscosity extracts usingS03 has heretofore been found to result in the formation of completelyintractable sludges.

In carrying out the process according to our invention, suitableextracts are selected having the specified high viscosity, for example,heavy neutral extracts and bright stock extracts resulting from thesolvent refining of heavy lubricating oil stocks and the like with theusual refining solvents such as, for example, liquid sulfur dioxide,nitrobenzene, furfural, dichloro-diethylether, phenol, etc.

The viscous extract is mixed with a suitable inert liquid selected, asspecified hereinafter, not only for its ability to reduce the viscosityof the resulting mixture of extract and liquid to a sufficiently fluidstate to permit ready agitation at the sulfonation temperatures, butalso for its ability to homogenize all the components of the extract andsubstantially to inhibit separation of the sludge com,- ponents as wellas to dissolve the unreacted sulfonatable hydrocarbons and theirresulting sulfonation products. The extract-inert liquid mixture is thensubjectedv to sulfonation with sulfur trioxide gas used either alone, or

Patented Nov. 6, 1956 preferably, diluted with an inert gas such asnitrogen or air, until the sulfonation reaction is complete. Theoilsoluble sulfonic acids thus produced may then be recovered by anysuitable means, for example, by volatilizing the inert liquid in thepresence of steam. The residue may then be mixed with a water immisciblesolvent for the oil-soluble sulfonic acids, such .as petroleum ether,and, if desired, additional water is added whereupon the mixturestratifies into an oil layer, containing the 'oilsoluble sulfonic acidsand a water layer.

We have found that in general, yields of oil-soluble sulfonic acids willamount to between about 30% .and about 70% based on the weight of theextract sulfonated, using extracts of the character specified.

Our process is adapted for carrying out sulfonation of the crude highviscosity extracts of virgin heavy lubrieating oil stocks, utilizing thetotal of such extracts without prior treatment or purification thereofeither by distillation, extraction, sludge removal or other treatment.Our process is adapted to utilize extracts of this character havingviscosities of at least about 100 SUS at 210 F. and is particularlyadapted for the sulfonation of extremely high viscosity extracts havingviscosities up to 3500 SUS at 210 F. or higher and in general stockshaving viscosities between about 150 and about 500 SUS at 210 F. arepreferred.

The inert organic liquids which may be used as a medium for carrying outthe sulfonation reaction may be any nitro or chloro aromatic or chloroaliphatic hydroor halohydro-carbons which are liquids at the sulfonationtemperatures and especially those having from 1 to 5 carbon atomsinclusive and from 1 to 4 chlorine atoms. Illustrative of such suitableorganic liquids are nitrobenzene, monochlorobenzene, nitrotoluene,orthodichlorobenzene, ethylenedichloride (1,2-dichloroethane),1,1-dichloroethane, l,l,2,2 tetrachloroethane, 1,1,1 trich'loroethane,tetrachloroethylene (1,1,2,2-tetrachloroethene), methylene chloride(dichloromethane), chloroform, carbon tetrachloride,trichloromonofiuoromethane, 1,2-dichloropropane, l-chlorobutane, themono and dichloropentanes, liquid mixtures of chlorinated naphthalenes,and-mixtures of "any of the above.

If the original extraction liquid was one of the suitable sulfonationliquids named above, it need not be removed from the extract, but may beused as the sulfonation liquid, supplemented, if necessary, withadditional quantities of the same or a difierent liquid of the characterdescribed. Since nitrobenzene is commonly used as an extractant forheavy lubricating oils to produce extracts of a character utilizable inour process, this liquid is one of our preferred sulfonation liquids insuch cases. Another especially valuable sulfonation liquid is ethylenedichloride because of its cheapness and its favorable boiling point(83.5 C.) which is high enough to prevent undue losses by volatilizationand yet low enough to be very readily removable, as by steamdistillation, after completion of the sulfonation reaction.

The quantity of inert liquid used is not critical but should besuflicient to bring the viscosity of the resulting mixture to a suitablylow level to permit easy agitation and to dissolve or homogenize thehard sludge which forms upon sulfonation of the extracts. As small aquantity as will suffice for these two purposes is preferably used, asthe inert liquid must be removed for final recovery of the sulfonicacids.

Difierent quantities of the different liquids will be needed, dependingon the sludge forming character of the extract material to besulfonated. In general, quantities of liquid equal to at least about byweight based on the weight of the extract, preferably quantities betweenabout 50% and about 150% on the same basis are used. For certainextracts which yield unusually heavy sludges on sulfonation, somewhatlarger proportions of liquid diluent may be necessary for example up toabout 500% based on the weight of the extract. Such dilutions producereaction media which maintain mobilities of the general character ofwater or similar low viscosity liquids, during sulfonation and arevirtually free from sludge.

Sulfonation is carried out by sulfur trioxide gas, which may be obtainedfrom any suitable source, for example, as sulfuric acid plant convertergas, stripped from oleum, or vaporized from stabilized liquid sulfurtrioxide (Sulfan). The S03 gas may be used alone, but preferably shouldbe diluted with inert gas such as nitrogen or air to reduce charring anddecomposition.

Sulfonation temperatures may vary over a wide range, but preferablyshould be maintained between about 10 C. and about C.

The time required to complete the sulfonation reaction in batchoperations will vary somewhat with the fluidity of the reaction mixture,the strength of the S03 gas stream, and the intimacy of contact of the$03 with the sulfonatable components of the extract. In any event,sulfonation is quite rapid and, with adequate agitation, will usually becomplete in a period between about 5 minutes and about 70 minutes. Incontinuous operation, residence times required will be even smaller.

Recovery of the resulting oil-soluble sulfonic acids may be effected inany suitable manner, for example, by removal of the inert liquid as byvolatilization, followed by extraction of the residue with awater-immiscible solvent for the sulfonic acids, aided, if desired, byprior addition of water or steam to cause separation of the crudematerial into water and oil layers and recovery of oil-soluble sulfonicacids from the oil layer. When the sulfonation mass contains inertliquids which have relatively low boiling points, steam distillationprovides a convenient method for volatilizing the inert liquid, andleaves suffi'cient quantity of water in the residue to form a layercontaining the water-soluble impurities upon addition of awater-immiscible solvent for the oil-soluble sulfonic acids.

The sulfonic acids are readily converted to their salts such as thealkali metal, alkaline earth metal and other metallic salts, and areuseful in these salt forms for many purposes. The alkaline earth metalsalts, especially the barium and calcium salts are useful as lubricatingoil additives, in rust-proofing compositions etc. The alkali metalsalts, such as the sodium salts are often prepared as an intermediatestep to the preparation of other metallic salts, and may be merchandisedin such form. Our invention therefore contemplates the metallic salts ofthe sulfonic acids as well as the acids themselves.

The following specific examples will further illustrate the invention.Parts are by weight except as otherwise noted.

Example 1 491 parts of an extract having a 338 SUS viscosity at 210 F.,and molecular weight of 490, obtained by furfural extraction of apropane deasphalted mid-continent vacuum residuum, was placed in areaction vessel equipped for agitation, and 250 parts of nitrobenzenewere added thereto yielding a homogeneous solution with the extract.Sulfur trioxide vapor diluted with dry air to form a mixture containingapproximately 35% by volume of S03 was introduced into the mixtureduring a period of 15 minutes at a temperature ranging from 42 C. to 53C., using an external cooling bath, until 70 parts by weight of S03 hadbeen added. The mixture remained homogeneous throughout the reactionperiod, and agitation was in no way impeded by the development of sludgeor high viscosity. The sulfonated mixture was freed from nitrobenzene bysteam distillation and the resulting mixture was found to containoil-soluble sulfonic acids equal to a 49% yield, based on sulfurtrioxide used, or 51% based on the crude extract, as calculated on thebasis of the molecular weight of the crude given above, and of'thesodium salt as 592.

The sulfonic acids were extracted from the mixture with petroleum ether,to which was then added 150 parts each of water and isopropyl alcohol.This solution was neutralized with solid barium hydroxide, and vacuumdried to produce the barium salt of the sulfonic acids.

Example 2 1000 parts of an extract, having a 111 SUS viscosity at 210 F.(obtained by furfural extraction of a raw vacuum-distilled heavy neutrallubricant fraction of midcontinent origin and having a SUS at 210 F. of60) was placed in a reaction vessel equipped for agitation, and 600parts of ethylene dichloride added thereto yielding a homogeneoussolution with the extract. Sulfur trioxide vapor diluted with dry airwas introduced into the mixture during a period of 16 minutes at atemperature ranging from 33 C. to 42 C., using an external cooling bath,until 100 parts by weight of S03 had been added. The mixture remainedhomogeneous throughout the reaction period, and agitation was in no wayimpeded by the development of sludge or high viscosity. After removal ofthe ethylene dichloride by steaming, the mixture was treated withpetroleum ether, yielding an oil layer and a water layer. The oil layerwas titrated and found to contain 50% of oil-soluble sulfonic acidsbased on sulfur trioxide used, according to the equation The sulfonicacids were then converted to their sodium salts by diluting the oillayer with 150 parts each of water and isopropyl alcohol, andneutralizing the mixture with caustic soda solution. The mixture wasthen vacuum dried, the sodium salts isolated in a yield of 29% by weightbased on the original extract.

Examples 3 to 8 Additional tests were carried out according to theprocedure described in Examples 1 and 2. The quantities and character ofthe extracts and the inert sulfonation liquids, together with theresults obtained, are listed in Table I below which also includes thedata of Examples 1 and 2. In Example 3, ethylene dichloride was used asthe extractant for the oil-soluble sulfonate. In no case was anydifiiculty experienced with sludge during the sul- Examples 1 0-22Example No.

Insert Liquid Nitrotoluene.

1,1-dichloroethane. 1,1,2,2-tetrachloroethane. 1,1,1-trichloroethaue.

tetrachloroethylene (1,1,2,2-tetrachloroethene) methylene chloride(dichloromethane). chloroform (trichloromethane) carbontetrachloride(tetrachloromethane) trichloromonofluoromethane. 1,1-diehloropropane.

l-chlorobutane.

secondary amyl chloride (2-chloro-pentane). amylene dichloride(dichloropentane).

In all cases the mixtures remained homogeneous and fluid throughout thesulfonation reaction period, and agitation was in no way impeded bydevelopment of sludge or high viscosity.

While the above describes the preferred embodiments of the invention itwill be understood that departures may be made therefrom within thescope of the specification and claims.

We claim:

1. A process for preparing oil-soluble sulfonic acids which comprisescontacting with sulfur trioxide gas, in a single step, as temperaturesbetween about 10 C. and about 70 C., an aromatic petroleum extracthaving a Saybolt Universal viscosity at 210 F. of at least about 100seconds, in the presence of at least about 25% by weight of an inertliquid selected from the group consisting of chloroalkanes,chlorofiuoroalkanes, chlorinated mononuclear and binuclear aromatichydrocarbons, and nitromononuclear aromatic hydrocarbons whereby asulfonation product free from troublesome sludge is obtained.

2. The process of claim 1 wherein the extract is a crude extractresulting from the solvent refining of a virgin heavy lubricating oilstock.

fonatlon. 3. The process of claim 2 wherein the extract has a TABLE IExtract Solvent Example Sulfur Temp. Time Yield Number Trioxide (C.)(Min.) (Per- YP SUS at ype (Parts) (Parts) cent) 210 F. (Parts) 1Mid-Continent Bright Stock... 338 491 Nitrobeuzene 250 70 42-53 15 49 2Mid-Continent Heavy Neutral- 111 1000 Ethylene Dichloride 600 100 33-4216 50 3. West Coast... 450 491 Nitrobeuzeue 200 89 40-67 17 35 4...-..d0 450 354 Ethylene Diehlonde 310 63 3255 13 46 5. Mid-Continent Bht Stoc 3, 300 496 Nltrobeuzene 234 80 3654 15 45 6. d0 3, 300 476Ethylene Dichlorrde 307 80 26-55 17 38 7 Mid-Continent Heavy Neutral.148 506 Nitrobeuzene 229 80 33-46 22 68 8 do 148 404 Chlorobenzene 30564 33-50 12 48 Example 9.C0nversi0n of oil-soluble sulfonic acids tosodium salts 955 parts of the petroleum ether layer, containingoilsoluble sulfonic acids prepared according to Example 7 wasneutralized with 187 parts of a 10% aqueous caustic soda solution in thepresence of 150 parts of isopropyl alcohol. The resulting solution wasfreed of petroleum ether, isopropanol and water by heating in vacuo on awater bath to constant weight (425 parts). The final product sodiumsulfonate dissolved readily in petroleum oils and in organic solventssuch as xylene. The yield amounted to 54% as sodium sulfonates, based onthe weight of the original extract as calculated from its molecularweight of 406.

Saybolt Universal viscosity at 210 F. of between about seconds and about3500 seconds.

4. The process of claim 2 wherein the inert liquid is selected from thegroup consisting of nitro and chloro mononuclear aromatic hydrocarbons.

5. The process of claim 2 wherein the inert liquid is a chlorinatedaliphatic hydrocarbon having from 1 to 5 carbon atoms inclusive and from1 to 4 chlorine atoms.

6. The process of claim 2 wherein the inert liquid is nitrobenzene.

7. The process of claim 2 wherein the inert liquid is ethylenedichloride.

8. The process of claim 2 wherein the inert liquid is monochlorobenzene.

aveasse 9. A process for preparing oil-soluble sulfonic acids whichcomprises contacting with sulfur trioxide gas in a single step, attemperatures between about 10 C. and about 70 C. a crude aromaticpetroleum extract resulting from the solvent refining of a virgin heavylubricating oil stock, having a Saybolt Universal viscosity at 21-0 F.between about 100 seconds and about 3500 seconds, in the presence ofbetween about 25% and about 500% by weight of an inert liquid selectedfrom the group consisting of nitro and chloro mononuclear aromatichydrocarbons and chloroalkanes whereby a sulfonation product free fromtroublesome sludge is obtained.

References Cited in the file of this patent UNITED STATES PATENTS

1. A PROCESS FOR PREPARING OIL-SOLUBLE SULFONIC ACIDS WHICH COMPRISESCONTACTING WITH SULFUR TRIOXIDE GAS, IN A SINGLE STEP, AS TEMPERATURESBETWEEN ABOUT 10* C. AND ABOUT 70* C., AN AROMATIC PETROLEUM EXTRACTHAVING A SAYBOLT UNIVERSAL VISCOSITY AT 210* F. OF AT LEAST ABOUT 100SECONDS, IN THE PRESENCE OF AT LEAST ABOUT 25% BY WEIGHT OF AN INERTLIQUID SELECTED FROM THE GROUP CONSISTING OF CHLOROALKANES,CHLOROFLUOROALKANES, CHLORINATED MONONUCLEAR AND BINUCLEAR AROMATICHYDROCARBONS, AND NITROMONONUCLEAR AROMATIC HYDROCARBONS WHEREBY ASULFONATION PRODUCT FREE FROM TROUBLESOME SLUDGE IS OBTAINED.